Toggle closures are commonly used for dispensing creams, lotions, and other thick liquids from resilient containers. Toggle closures offer consumer recognized conveniences over simple threaded closures. For example, toggle closures permit one handed manipulation with a simple one finger push-to-open and push-to-close operation. When used with creams and lotions, the common means to dispense is to squeeze the resilient container. Hence, toggle closures of the type generally known in the art have been suitable for dispensing small quantities of these products upon each operation. However, using such prior art toggle closures to dispense larger quantities of thinner liquids produces an undesirable result. Bi-directional flow through a common conduit produces severe glugging, splattering and slow dispensing. Squeezing the resilient container can overcome the glugging problem, but may be cumbersome with larger containers. In addition, multiple squeezes of the container may be required.
With larger liquid containers, for example, 40 ounces or more, the liquid head pressure may also be sufficient to cause resilient collapsing of the container as the liquid is dispensed. The resilient collapsing will provide partial glug-free dispensing but when the vacuum created by dispensing of the liquid is insufficient to cause further collapsing of the container, glugging will occur.
Providing a second conduit for venting air into the container during dispensing will eliminate glugging. Toggle or pivotable type closures which would satisfy this requirement are known in the art. For example, U.S. Pat. No. 3,734,359 issued to Waterman on May 22, 1973 admits atmospheric pressure through an air vent opening when a pivotable element is in the open position for dispensing. U.S. Pat. No. 4,487,342 issued to Shy on Dec. 11, 1984 discloses a toggle closure having an air intake path which admits ambient air to provide a smooth discharge flow of fluid from an effluent pipe and toggle port.
However, in both of the aforementioned U.S. Pat. Nos. 3,734,359 and 4,487,342, the air vent is intended for use only as an air vent. In both cases, the air vent path from the container opens into a chamber in the closure. Resilient collapsing of the container would result in flooding of the air path and liquid flow into the generally open chamber, which is necessarily open to provide the required venting. This flooding would result in severe leakage of the container's liquid contents from the closure. Once flooded, there would be little differential liquid head pressure available to cause the air vent to return to its intended function, and the container would have to be returned to an upright position and the liquid dispensing cycle stopped to clear the vent. As thin wall plastic is becoming more and more common in container structures, tolerance to container collapsing or squeezing, whether intended or inadvertent, is highly desirable.